Assembly behavior, structural characterization and rheological properties of legume proteins based amyloid fibrils

The assembly behavior of three selected legume proteins was monitored using thioflavin T (ThT) fluorescence intensity, atomic force microscopy (AFM) and dynamic light scattering (DLS) in this test. It was found that the cowpea protein (CoP) had the highest ability to form amyloid fibrils due to the higher ThT fluorescence intensity of CoP fibrils than chickpea protein (ChP) fibrils and lentil protein (LP) fibrils. These legume proteins were partially denatured during initial heating period, and then the elongation of fibrils was occurred with prolonged heating time. Correspondingly, the particle size of legume proteins decreased firstly, probably resulting from the degraded polypeptides and disrupted structure under the heat treatment and acid hydrolysis. Then the particle size of proteins increased with increasing heating time due to the reorganization of ordered structure. From the results of SDS-PAGE and AFM, vicilin fractions were more beneficial to the formation of fibrils, and the longer and flexible fibrils were observed in the vicilin enriched CoP fibrils, whereas the semiflexible fibrils and rigid fibrils were occurred in LP and ChP fibrils, respectively. In addition, the rheological properties of CoP fibrils were superior to ChP and LP fibrils, owing to the tight entanglement of the longer and flexible CoP fibrils. This work will strengthen the understanding of the formation mechanism of different legume proteins based fibrils and explore their potential application.